1. Field of the Invention
This invention relates to sanitary engineering valves, in general, and to a change valve for selecting a bath tub faucet or a shower head for water discharge, in particular.
2. Description of the Prior Art
In certain such prior change valves, a valve spindle pushes a double-valve disc backwards and forwards for alternative direction of outflow between valve seats for bath and shower outlets. Automatic return from the shower outlet position to the bath outlet position when the water supply is cut off is typically provided by means of a spring which pushes the valve disc back into the bath outlet position. However, this arrangement requires a relatively powerful return spring to overcome the frictional resistance of a seal on the actuating spindle. Because of the reciprocating action between the valve disc and the actuating spindle, a relatively high operating pressure is required in the change valve to provide proper operation and this, in many cases, is not or is only seldom obtainable from the water supply system. Under low water pressure conditions, the prior change valves cannot be used or can only be used with restrictions.
German Patent Specification No. 901,278 teaches an arrangement whereby the valve disc is arranged separately in the housing to overcome the above shortcomings. Actuation is provided by a low pressure device tappet making non-positive connection with the valve pistons. One disadvantage of this device is that the valve disc can only be moved in one direction to close the bath outlet. The bath outlet can only be opened by blocking the water in-flow by means of the return spring.